Suzaku Observations of the Galactic Center Microquasar 1E 1740.7-2942

Abstract

We present two Suzaku observations of the Galactic center microquasar 1E 1740.7-2942 separated by approximately 700 days. The source was observed on both occasions after a transition to the spectrally hard state. Significant emission from 1E 1740.7-2942 is detected out to an energy of 300 keV, with no spectral break or turnover evident in the data. We tentatively measure a lower limit to the cut-off energy of ~ 380 keV. The spectra are found to be consistent with a Comptonized corona on both occasions, where the high energy emission is consistent with a hard power-law (Γ~ 1.8) with a significant contribution from an accretion disc with a temperature of ~ 0.4 keV at soft X-ray energies. The measured value for the inner radius of the accretion disc is found to be inconsistent with the picture whereby the disc is truncated at large radii in the low-hard state and instead favours a radius close to the ISCO (R_in ~ 10 - 20 R_g).

8 pages, 4 figures, formatted using emulateapj.cls. Accepted for publication in ApJ

References in corpus (9)

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Cited by in corpus (8)

• The X-ray Spectral Evolution of Galactic Black Hole X-ray Binaries Toward Quiescence
• The XMM-Newton view of the central degrees of the Milky Way
• The accretion-ejection coupling in the black hole candidate X-ray binary MAXI J1836-194
• A Swift survey of accretion onto stellar-mass black holes
• X-ray Emission from Transient Jet Model in Black Hole Binaries
• NuSTAR and INTEGRAL observations of a low/hard state of 1E1740.7-2942
• Confirming the thermal Comptonization model for black hole X-ray emission in the low-hard state
• Broadband X-ray properties of black holes GRS 1758-258 and 1E 1740.7-2942: AstroSat and NuSTAR results